Physical Simulation Study on Excavation of Multi-Tunnel Intersection

The surrounding rock deformations and reinforcement methods in the excavation of the 3-lb node—which was an extremely complicated multi-tunnel intersection in Jinping Hydropower Station II—were researched in this paper, with model test and field monitoring employed. Results from the model test showed (1) the excavation of the later tunnel would greatly enlarge he deformations of the vault and side walls itself, as well as that of the existing tunnels nearby, (2) large deformations at the middle of high side walls were outstanding, (3) the spots where the tunnels intersected with an acute angle were the weakest parts of the multi-tunnel intersection, and the weakest parts would not collapse if reinforced by a column although other parts would The recommendations from the model test applied in the excavation of the 3-lb node ensured the safety of the tunnels, which had been proved by the field monitoring data. Research in this paper could serve as references for the excavations of other intersected tunnels in the Jinping Power Station II.